Good point about the possible skin allergy, Chris. I think this thread has identified three possible lines of diagnosis - feather pecking, (addressed by beak bits) environment in the run and coop, (as in Chris's enquiry) and feeding.
The hen in the pic looks like an ordinary brown high-performance egg laying hybrid, the kind you'd find on commercial farms, like the ones that get rehomed as exbatts. Are they all the same, Dye, and from the same supplier at the same time? If so, possibly genetics and nutrition may have something to do with it. Fast-track hybrids are bred to produce eggs, eggs and more eggs, and feather condition is probably a relatively minor factor, given the conditions factory farmed hens have to live in. They definitely need a high-performance food to cope with both egg laying and feather maintenance, out of doors in winter.
I think that, whatever you are feeding them, it would be an idea to change to one of the leading brands recommended previously in this thread, in case the pellets you're using contain something they are reacting to, or are not giving them the full range of nourishment they need. I'm not saying that what you're giving them is inadequate, just that a change to a top-quality brand would rule out allergies or deficiencies. This may be more important than adding supplements, which may not be what is needed.
Then, if they're perching OK off the floor at night, and as you say, you keep them clean and they have relatively sheltered living conditions, and are clear of parasites, then maybe you will have all three bases covered!

Hens are very easily stressed by any change in their lives, and this often results in egg production dropping. Unless you went into the coop at night when they were sleeping, you've probably been doing a fair bit of chasing around in the attempt to catch them all to fix their beak bits. Some of them will have been caught and had an unsuccessful attempt which they didn't like, and others won't have enjoyed the handling and fitting where you were successful. Hens are a prey species, and any attempt to catch and handle them is going to be upsetting for them, unless they are very tame individual pets who tolerate being cuddled every day. Panic spreads quickly through a flock, although you can't help it sometimes.Also, whilst you'd think it was lovely for them to have even more room to roam in the garden, this is another change and they may have had to pluck up courage to take the plunge and explore new territory, hence some extra stress. Add to this the fact that your hens are somewhat off colour, for reasons we haven't fully worked out yet, and that it's still dark mid-winter, when egg production is low anyway, so it's not very surprising that they're withholding their eggs for a while. Once you get all the beak bits on, things should settle down and return to normal, and then you'll be able to see if preventing any possible pecking is having the right effect. When they do start feathering up again, this may be at the expense of eggs because if they really get going on their new plumage, they may not have energy or resources for eggs as well.
Are they all brown hybrids, or are there some mixed breeds in there, Dye? And where did you get them from?

hi again after the past 3 to 4 days ive noticed loads of feathers lying around and the hens all have clips on beeks so could they be moulting hence no eggs well odd 1 now , they were 18 weeks old roughly in march last year

That's quite strange.
I don't think there's anything else you can do, Dye - so long as you've followed all the advice on feeding, and have got all their beak bits fitted, you'll just have to be patient and see what happens in the next month. Just let them get used to the bits, at least you know that whatever feather loss you can see is not down to pecking, so either it will clear up in time, or you'll know something else is going on. As for the eggs, just give it time - they may well be going to start feathering up and be putting strength into getting ready to do this, so they might be shutting down on egg production to do this.
What colour are their combs? Bright red, or a bit paler pink?

Thats good. Bright red combs are what is going to happen around this time of year - they are getting 'hot' for the new breeding season with the lengthening daylight even though it still seems like the middle of winter.
If they are moulting now then make sure they have good shelter as it is going to get colder before it gets warmer and now isn't a good time to be without a full coat of feathers but you should also see that bare bottom thing clear up pretty soon.
Chickens do some pretty weird things that sometimes defy common sense! The most you can do is make sure they are eating well for the time of year, keep the parasites in check and look out for any that seem particularly subdued (i.e. withdrawn and hunched up.) If all seems well after that then even if they are oddly without feathers then you shouldn't worry too much as you will likely be fretting over things you cant know or change.
Chickens are tough and there needs are simple. Its our responsibility to keep an eye out for the unusual but that is definitely not a precise science - bless 'em!

ye they have good shelter i have also covered there run with straw so they can forrage keeping there minds active also vitamin stuff in water and corn every other day to put fat on them to keep warm usually on the evening so they have a full crop

wow since i put the beek bits on ive given my hens game bird pellets and amazingly every hen have a full body of new pins coming through looks like it wont be long before there feathered again also starting to get eggs again 4 today from 13 not bad its a start thanks all for help ill keep you updated